Method and apparatus for detecting irregularities in a moving sheet of yarn



METHOD AND APPARATiIS FOR DETECTING IRREGULARITIES IN A MOVING SHEET OF YARN Filed Jan. 8, 1968 June 3, 1969 5 COST ET L I ,4 2

INVENTOR S Szeme fiasi 6' m d/61 #Wm/wz United States Patent 3,447,213 METHOD AND APPARATUS FOR DETECTING IRglEGULARITIES IN A MOVING SHEET 0F Y RN Sieme Dost, Emmen, and Michiel J. Duncker, Arnhem, Netherlands, assignors to American Enka Corporation, Enka, N.C., a corporation of Delaware Filed Jan. 8, 1968, Ser. No. 696,242 Claims priority application Netherlands, Jan. 11, 1967, 6700367 Int. Cl. D02h 13/08; D03d 45/10, 51/28 US. C]. 28-51 11 Claims ABSTRACT OF THE DISCLOSURE Method and apparatus for detecting irregularities in a moving sheet of yarn particularly during a warping process with at least two photoelectric detecting means spaced along the path of the moving sheet which comprises producing a signal with a first photoelectric detecting means when an irregularity in the sheet is observed thereby, -reducing the speed of the sheet in response to said signal, producing a second signal with a second photoelectric detecting means spaced downstream of the first detecting means when the same irregularity is observed thereby and stopping the movement of the sheet in response to the second signal.

This invention relates to a method and apparatus for detecting slubs and/or other irregularities in a moving sheet of yarns, threads or the like filamentary materials. More particularly, this invention relates to a method especially suitable in the warping process, for detecting irregularities in a yarn sheet with at least two photoelectric detecting means which are spaced along the direction of travel of the yarn sheet, and which can provide a warning signal or a signal to stop the sheet upon detection of an irregularity and to an apparatus for carrying out this method.

A method and apparatus similar to those of this invention are known. The known apparatus is often so constructed that two photoelectric detecting members produce a signal which, by way of a transmission system, stops the yarn sheet moving along at the normal or usual operating speed of, for instance, 400 meters per minute. Although in the case of high-quality yarns the number of irregularities, more particularly slubs, in each of the yarns mostly used in warping is relatively low, the warping machine is with this known method and apparatus stopped rather frequently by one of the detecting members.

This rather high frequency of stops occurs because in the warping process use is mostly made of a yarn sheet consisting of from a few hundred to a few thousand parallel yarns and because the warping machine must be stopped every time a slub in any one of the yarns of the sheet passes the detecting member.

In the known apparatus each photoelectric detecting member substantially consists of a light source, which is located on one side of the yarn sheet and which emits its light beam across the top and the bottom of the yarn sheet to a photoelectric pickup located on the other side of the yarn sheet. After one of the detecting members has stopped the warping machine and the yarn sheet, the warper, i.e. the operator, has to find the slub in the yarn sheet, remove the slub and put the machine in operation again. It has been found that in the known method of detecting slubs, finding the detected slub is very timeconsuming and in a considerable percentage of the cases where a slubis detected by the detecting members or 3,447,213 Patented June 3, 1969 ice the warping process is stopped no slub can be found. The last mentioned situation is often referred to as a false stop of the machine, which implies that the detecting member has not been excited by a slub but, for instance, by a vibrating yarn in the sheet or by false external light reflected by the yarns. Such disturbances may exert an influence on the detecting member that is similar to that exerted by real slubs. In the known method for detecting slubs in the warping process, particularly as a result of the difficulty of finding the slubs and the false stops, there is a loss of production time which may amount to twenty to thirty percent.

Advantageously this invention provides a method and apparatus which do not show the disadvantages of the above-described method and apparatus.

Thus this invention comntemplates a method of detecting irregularies in a moving sheet of yarn or like filamentary material, particularly in the warping process during the winding of the yarn sheet from or onto a yarn package, with the aid of at least two photoelectric detecting means placed one after the other along the path of the yarn sheet, which comprises producing a signal with a first photoelectric detecting means when an irregularity in the sheet is observed by the first detecting means, reducing the speed of the yarn sheet in response to the signal, producing a second signal with a second photoelectric detecting means spaced downstream of the first detecting means when the same irregularity is observed by the second detecting means and stopping the movement of the yarn sheet in response to the second signal.

In the method of this invention it has been found that when the second detecting means stops the movement of the sheet, the yarn sheet is, because of its lower speed, arrested relatively rapidly so that the observed slub will always be found at practically the same relatively short distance downstream of the second detecting means. Moreover, by the method of this invention the percentage of false stops of the warping machine will practically be reduced to zero because the second photoelectric detecting means observes the yarn sheet in a steadier condition. Advantageously, the method according to the invention will produce good results if in the case of detection of an irregularity by the first detecting means, the speed of the yarn sheet is reduced to a value which does not exceed about percent of that of the normal or usual operating speed of the sheet.

The method of this invention is particularly effective when a correction signal is produced for increasing the speed of the yarn sheet to the normal operating speed if the irregularity in the yarn observed by the first detecting means is not observed by the second detecting means. In accordance with this invention the correction signal can be produced in a simple manner by a time switch, which is actuated by the output signal of the first detecting means. The time switch may be stopped by an output signal of the second detecting means.

The preferred embodiment of the method of the invention is characterized in that the output signals of the first and the second detecting means automatically reduce the speed of the yarn sheet and stop the yarn sheet, respectively, by way of a transmission means.

With advantage, the invention is further characterized in that the first detecting means, upon observing an irregularity, produces a signal for actuating the second detecting means, and in that after a predetermined time delay a correction signal is produced which deact-uates the second detecting means.

This invention is also directed to an apparatus for carrying out the above-described detection method, comprising a frame; means, provided with a driving means or mechanism and a transmission means, for winding or unwinding a sheet of a large number of parallel yarns or like filamentary materials; guide means for guiding the yarns substantially in one plane; and at least two photo'- electric detecting means spaced some distance apart along the path of the yarns for detecting slubs and/or other irregularities in the yarns and for controlling operation of the driving means. The first detecting means is, via the transmission means, so coupled with the driving means that when the first detecting means observes an irregularity in the yarn, the speed of the yarn sheet is reduced, and the second detecting means, placed downstream of the first detecting means, is so coupled with the driving means via the transmission means, that if the same irregularity is also observed by the second detecting means, the movement of the yarn sheet is stopped.

The invention will be further described with reference to the accompanying schematic drawings of an embodiment of the invention in which;

FIGURE 1 represents a schematic side view of the apparatus of the invention positioned along the path of the yarn sheet on a warping machine; and

FIGURE 2 represents a schematic plan view of the apparatus on the warping machine, including a block diagram of the detecting means of the invention.

In the FIGURES 1 and 2 the reference number 1 designates a yarn sheet composed of a few thousand yarns on a warping machine. Each of the yarns is supplied to the warping machine 2 in the direction indicated by an arrow from a creel (not shown), which, as viewed in the drawings, is mounted on the left end of the apparatus. In the creel each yarn of the sheet 1 is unwound over-end from a yarn package 3. The schematic FIGURE 1 only shows one of the yarn packages. Before the yarns reach the warping machine 2, they are passed through a number of guiding members (not shown). The warping machine comprises a frame (a portion of which is shown in FIGURE 2 and designated by reference numeral 2') which carries the essential parts of the apparatus of the invention.

As can be seen from FIGURES 1 and 2, the apparatus of the invention including the warping machine, viewed in the direction of movement of the yarn, successively comprises an eyeboard 4, a guide bar 5 with a felt strip 6, a reed 7 for separating the yarns, a first detecting means including a light source 8 and a photoelectric pickup 9, a guide bar 10, a reed 11, a second detecting means including a light source 12 and a photo electric pickup 13, a member 14 for detecting broken ends in the sheet 1, a reed 15, a guide bar 16, and a yarn package or warp beam 17. The warp beam can accommodate a yarn sheet that is dozens of kilometers long and is in an appropriate manner rotatably mounted in the frame of the warping machine. Moreover, the warp beam 17 is provided with an appropriate driving and control mechanism 18 (shown in FIGURE 2) for rotating the Warp beam at the desired speed.

The method and apparatus of this invention for detecting slubs or other irregularities in the yarns of the yarn sheet 1 will now be further described particularly with reference to the block diagram in the lower part of FIGURE 2. The light beams of the first and the second photoelectric detecting means are indicated by the reference numerals 19 and 20, respectively. Each light beam travels partly below and partly above the yarn sheet 1 in a direction transverse to the direction of the movement of the sheet. The direction of movement or travel of the yarn is indicated by an arrow 21. When a slub or some other irregularity in one of the yarns of the sheet 1 passes through the light beam 19 emitted by the first detecting means, the light beam is temporarily more or less interrupted. As a result, the pickup 9 produces a signal, which may be appropriately amplified or transduced, and which is supplied to the control and driving mechanism 18 of the warp beam 17 by way of a lead or line conductor 22. In the housing accommodating the mechanism 18 the 4 signal, by way of a suitable transmission means, effects a reduction of the speed of the yarn sheet to a value which is, for instance, not more than about of that of the normal operating speed.

Moreover, the output signal of the pickup 9 actuates the pickup 13 of the second detecting means via the lead or line 23. The output signal of the pickup 9 is, by way of the lead 24, also supplied to the time switch 25. The circuit (of the apparatus) and the transmission means must be such that the yarn sheet 1 moves at the reduced speed before a slub which has been observed by the first detecting means reaches the second detecting means. As soon as this slub passes through the light beam 20, the pickup 13 supplies, via lead 26, a signal to the control and driving mechanism 18. As a result, the warp beam 17 and the yarn sheet 1 are stopped. By way of the lead 27 the output signal of the pickup 13 also stops the time switch 25. Consequently the time switch is immediately reset to its initial position.

When the yarn sheet 1 has in the above-described way been automatically stopped, the warper i.e. the operator, seeks the slub in the yarn sheet 1 and removes it. Owing to the reduced speed of the sheet and the rapid switching and braking of the apparatus the slub will, after the yarn sheet 1 has been stopped, be found along the area designated by the dash line 29 which is a practically constant distance (designated by reference numeral 28) upstream of the light beam 20. The warper then manually re-starts the machine, the yarn sheet 1 regaining its full speed and the pickup 13 being automatically put out of action.

Also when the pickup 9 detects a pseudo-slub (i.e. a false indication of a slub) the speed of the yarn sheet 1 is in the above-described manner reduced, the time switch 25 is started and the pickup 13 is put into action. When after a given time the pseudo-slub has not been observed by the pickup 13 of the second detecting means, the time switch 25, by way of the lead 30, supplies a correction signal to the control and driving mechanism 18 of the warp beam. As a result of the supply of the correction signal, the speed of the yarn sheet is, by way of the transmission means, returned to its normal operating value, and the pickup 13 is, via the lead 31, put out of action again.

While the novel features of the invention have been shown and described and are pointed out in the appended claims, it is to be understood that various omissions, substitutions and changes in construction and arrangement of the features shown and described may be made by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

1. A method for detecting slubs and other irregularities in a moving sheet of yarn during the winding of the yarn sheet in a warping process with the aid of at least two photoelectric detecting means placed one after the other along the path of the yarn sheet, which comprises producing a signal with a first photoelectric detecting means when an irregularity in the yarn sheet is observed by said first detecting means, reducing the speed of the yarn sheet in response to said signal, producing a second signal with a second photoelectric detecting means spaced downstream of the first detecting means when the same irregularity is observed by the second detecting means, and stopping the movement of the yarn sheet in response to the second signal.

2. The method of claim 1, in which upon observation of an irregularity by the first detecting means, the speed of the yarn sheet is reduced to a value which does not exceed about 85% of that of the normal operating speed.

3. The method of claim 1 which further comprises producing a correction signal if the irregularity observed in the yarn sheet by the first detecting means is not observed by the second detecting means and thereafter increasing the speed of the yarn sheet to its normal operating speed in response to said correction signal.

4. The method of claim 3 in which the correction signal also deactuates the second detecting means.

5. The method of claim 3, in which the correction signal is produced after a predetermined time delay by a time switch, which is actuated by the signal produced by the first detecting means.

6. The method of claim 5, in which the time switch is stopped by said second signal.

7. The method of claim 1, in which the signals produced by the first and second detecting means automatically reduce the speed of the yarn sheet and stop the yarn sheet, respectively, via a transmission means.

8. The method of claim 1, in which the signal produced by said first detecting means also actuates the second detecting means.

9. An apparatus for detecting slubs and other irregularities in a moving sheet of yarn which comprises means, provided with a driving means and a trans-mission means, for winding a large number of parallel yarns, guide means for guiding the yarns substantially in one plane, and at least two photoelectric detecting means spaced some distance apart along the path of the yarns for detecting irregularities in the yarns; a first of said detecting means being, by way of the transmission means, so coupled with said driving means that when the first detecting means observes an irregularity in the yarn, the speed of the yarn sheet is reduced, and the second detecting member, placed downstream of the first detecting member being by way of the transmission means, so coupled with said driving means that if the same irregularity is also observed by the second detecting means, the movement of the yarn sheet is stopped.

10. The apparatus of claim 9 in which there is provided a time switch which is coupled with the first detecting means.

11. An apparatus for detecting slubs and other irregularities in a moving sheet of yarns, which comprises warping means for transporting a sheet of yarns within a plane, and at least two photoelectric detecting means 5 coupled to the warping means, and arranged along the 15 ing means.

References Cited UNITED STATES PATENTS 1,768,746 7/1930 Cooker 2851 20 2,967,947 l/1961 Flook.

3,174,046 3/ 1965 Lindemann et al.

FOREIGN PATENTS 996,181 6/ 1965 Great Britain.

OTHER REFERENCES Warping Tricot Beams of Producer Twist Du Pont Nylon, Du Pont Technical Bulletin N-141; March 1961;

ROBERT R. MACKEY, Primary Examiner.

US. Cl. X.R.

ZOO-61.13; 226l0, 24; 250-219 

